FoxtrotOscar
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Joined: Wed Aug 28, 2013 9:13 am

64x32 LED display

Fri Aug 30, 2013 4:57 pm

Has anyone any reason why this might not be suitable for driving from a Pi?
Has anyone managed to control this display with the Pi? Or do I need to move to an Arduino :-(

http://www.embeddedadventures.com/led_m ... -6432.html


Image

The LDP-6432 is a dual-LED, tri-colour 64 pixel by 32 pixel LED matrix display. Each pixel consists of a red and green LED (commonly referred to as “1R1G”). There are 2048 pixels and 4096 individually addressable LED elements. It includes shift-register circuitry such that all 4096 LEDs can be controlled with only 11 microcontroller I/O lines. Pixels can show as black (that is, completely unlit), red, green or orange (red+green).

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bob_binz
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Location: Stockport, UK

Re: 64x32 LED display

Fri Aug 30, 2013 5:39 pm

Probably not too difficult to get going, here's the datasheet:

http://www.embeddedadventures.com/datas ... P-6432.pdf

However, bear in mind the comments about drive current - you won't be able to just connect it directly to GPIO so you'll need extra power circuitry etc.

FoxtrotOscar
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Re: 64x32 LED display

Fri Aug 30, 2013 5:53 pm

Thanks Bob,

I figured the power would need to be supplied separately - quite hefty at full bore :o , so no probs there.

My other option is to source a Jumbo LCD or large E-Paper display for my project - a legible @20-30m in full daylight countdown clock for sports functions. Main advantages there are the greater legibility through higher contrast ratios and lower power requirements. Cons - ££££ :!:

This one seems affordable though, and worth experimenting on for the beginning even though there's no data on display brightness...

Will I need a GERT or similar addon for this to work?
GND 1.....................2 A
GND 3.................... 4 B
GND 5.................... 6 C
EBNB 7.................. 8 D
RBB1 9................. 10 GBB1
RBB2 11............... 12 GBB2
GND 13................. 14 L
GND 15................. 16 S

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bob_binz
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Location: Stockport, UK

Re: 64x32 LED display

Sun Sep 01, 2013 9:24 am

FoxtrotOscar wrote: Will I need a GERT or similar addon for this to work?
GND 1.....................2 A
GND 3.................... 4 B
GND 5.................... 6 C
EBNB 7.................. 8 D
RBB1 9................. 10 GBB1
RBB2 11............... 12 GBB2
GND 13................. 14 L
GND 15................. 16 S
By GERT, do you mean the gertboard? That would work but is not "needed". As long as you use *some form* of buffer circuit to drive the LEDs you'll be fine.

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Burngate
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Re: 64x32 LED display

Sun Sep 01, 2013 10:27 am

I'm in the middle of something similar - though I'm using Adafruit's 32x16 tricolour panel.
It seems to work in much the same way as yours, so on that assumption ...

The Adafruit panel uses FD9802 shift-register-LED-driver chips (similar in operation to 74HC595, with extra current control), so you don't need to provide your own buffer circuit to drive the LEDs.
The input to the panel goes through a 74HC245 buffer, so as long as that chip can accept 3v3 inputs (I think it should, but theory and practice may differ) you (we!) can drive it from the Pi

Your panel needs 11 GPIOs - mine needs 12 - and the Pi has 17, so we should be ok there.

The only problem I foresee is the speed of the Pi.
We have to clock data into the panel four (six for me) bits at a time, for 64 (32 for me) bits in each string, before latching it, putting in the 4(3)-bit row address and enabling the output.
Rinse and repeat, 16(8) times in less than 20ms for reasonable refresh. If we want to do PWM-style variable brightness, we'll have to do it a helluvalot faster.
I'm not convinced that wiringPi or similar will be fast enough, so I'm going to write my own GPIO driver.

Actually I'm going to use RISC OS for mine, and write a module specifically for the panel.
Still, I'd be interested to find out how you've got on.

Re-edited for spelling & grammar

FoxtrotOscar
Posts: 25
Joined: Wed Aug 28, 2013 9:13 am

Re: 64x32 LED display

Wed Sep 04, 2013 12:16 pm

Hi Burngate,

Thank you for your feedback, and the info you provided.

It would be great to hang onto your shirt-tails during the dev. phase of this (our) project, and watching how you proceed over the various hurdles, if you don't mind. I am a newby to this sort of project, but I do have a good grasp of the general principals of screwing things up so it should be fun lol...

I now have my Pi, and so to eat it ;)
keep the info coming - and be careful out there.

Fi

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Burngate
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Re: 64x32 LED display

Wed Sep 04, 2013 4:09 pm

Of course, no problem :)
Do be aware, however, that the grey matter holds no records for speed, so if you grab the shirt-tails you're in danger of having to pull me along

FoxtrotOscar
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Re: 64x32 LED display

Mon Sep 09, 2013 8:35 pm

The display arrived today, damaged pins but appearing fine otherwise, so I'm ready to plug up and play :?

Helpppp!

FoxtrotOscar
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Re: 64x32 LED display

Wed Nov 06, 2013 8:47 pm

Right!

I need to write numbers to this display directly from the Pi via the driver board - but without using a USB lead.
I take it that the GPIO pins can be employed here for this.

I have heard mention of I2C - and I'm hoping some nice person will take me by the hand and show me how to code so that I can send a number or letter to the display in this fashion.

Python would be good as its the language I've picked to struggle through :? - although its not mandatory.

Thanks.

fixitsan
Posts: 58
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Re: 64x32 LED display

Wed Nov 06, 2013 9:21 pm

I've got one of Embedded Adventures 80 x 8 led boards here.
I cheated with the driving by getting their adaptive driver module for another few pounds, which does all the scanning/muxing and that means you only need to send it serial data straight from the Pi's UART.

Well worth the extra investment, because having to keep strict multiplexing timings can be a bother.

http://www.embeddedadventures.com/led_m ... 001v4.html
If yoiu have a PIC programmer grab the 6432 driver firmware from here and load it http://www.embeddedadventures.com/Tutor ... detail/140

Alternatively they can load the firmware for you.

As someone who has spent a lot of time programming for many different kinds of displays (Here's my 'universal' Smartsocket driver http://www.youtube.com/watch?v=ek8S4r7bBUU )
...I can tell you that unless you want a big part of your project to be an education in driving displays (rather than think of an interesting thing to do with them) then take as many shortcuts as possible, if they suit you.

Chris

FoxtrotOscar
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Re: 64x32 LED display

Wed Nov 06, 2013 10:02 pm

Hi Chris,
Yes, I do have that driver board and it's already talking happily to the display using Screamer from my pc.

What I'm looking for is writing characters from the pi through that driver just as you say.

Could you perhaps point me at an example of code to send a letter or number from the pi using the UART you mention?
I really am in the dark, but it'll not take much to illuminate the way...

Fi

fixitsan
Posts: 58
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Re: 64x32 LED display

Thu Nov 07, 2013 8:27 am

If yiou haven't already done so you need to reassign the serial port to make it user accessible. As standard the UART is assigned as the Pi's console. I searched these forums for clues like 'using serial port on Pi', and soon found the correct config files to play with, but it basically involved deletin references to the serial port in the boot scripts (I think serial port is ttyam0....or something similar)

Then I just used the driver's datasheet and sent the commands it requested, in ascii.

Sorry for not being more specific, but my Pi and the sample code is at home and I'm at work now, but if nobody else udates this thread later I'll post the code I used this evening when I'm home again.

Chris

fixitsan
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Re: 64x32 LED display

Thu Nov 07, 2013 9:30 am

I found some of the code I used, I already posted it on one of my groups....

At the top of the code....

Code: Select all

import serial
ser = serial.Serial()
ser.port = "/dev/ttyAMA0"
ser.baudrate = 9600
ser.bytesize = serial.EIGHTBITS #number of bits per bytes
ser.parity = serial.PARITY_NONE #set parity check: no parity
ser.stopbits = serial.STOPBITS_ONE #number of stop bits
ser.timeout = 1            #non-block read
ser.xonxoff = False     #disable software flow control
ser.rtscts = False     #disable hardware (RTS/CTS) flow control
ser.dsrdtr = False       #disable hardware (DSR/DTR) flow control
ser.writeTimeout = 2     #timeout for write

And then when i want to send something

Code: Select all

ser.open()
ser.write(chr(10)) # send chr 10
time.sleep(2) #pause 2 secs
ser.write("$B7E000000"+chr(13)+chr(10)) # send string "$B7E000000" and CRLF
And ser.close() when done....

FoxtrotOscar
Posts: 25
Joined: Wed Aug 28, 2013 9:13 am

Re: 64x32 LED display

Thu Nov 07, 2013 3:35 pm

Magic!

This is what I needed - thank you so much.
I'll play with this now and see how I get on, but it certainly looks like what I need.

fixitsan
Posts: 58
Joined: Sun Sep 29, 2013 4:28 pm

Re: 64x32 LED display

Thu Nov 07, 2013 6:29 pm

I'm curious to know how well the scrolling text works on that large display.

After speaking with the designer at Embedded Adventures it seems like they are willing to respond to requests to make the scrolling speed adjustable. I asked them if they could make it a user selectable parameter for my RSS feed reader which uses their 80 x 8 matrix display, I find the current scrolling speed is too slow and sometimes a bit glitchy.

If you get a minute to ask them (via email) if they can speed it up then they might get onto it more quickly ;)

Chris

FoxtrotOscar
Posts: 25
Joined: Wed Aug 28, 2013 9:13 am

Re: 64x32 LED display

Thu Nov 07, 2013 6:56 pm

Good idea.

On it.

OldManNoob
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Joined: Sat Dec 24, 2016 2:35 pm

Re: 64x32 LED display

Fri Jun 30, 2017 2:08 pm

Hi,
I'm trying to get this 64x32 panelto work using rPi3, serial PiZero addon, PLT2001 Matrix driver from EA and failing miserably :?

I'm attempting it with the code above, slightly (?) modded, and wonder if I'm on the wrong track altogether...

import serial
ser = serial.Serial()
ser.port = "/dev/ttyAMA0"
ser.baudrate = 15200
ser.bytesize = serial.EIGHTBITS #number of bits per bytes
ser.parity = serial.PARITY_NONE #set parity check: no parity
ser.stopbits = serial.STOPBITS_ONE #number of stop bits
ser.timeout = 1 #non-block read
ser.xonxoff = False #disable software flow control
ser.rtscts = False #disable hardware (RTS/CTS) flow control
ser.dsrdtr = False #disable hardware (DSR/DTR) flow control
#ser.writeTimeout = 5

ser.open()
ser.write('configpanel 64 32 0 2') # send config
ser.write('circle 2 10 10 10') # setup circle
ser.write('paint') #send
ser.close()

satadru
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Joined: Thu Apr 18, 2013 5:18 pm

Re: 64x32 LED display

Fri Jul 14, 2017 3:48 am

Did you have any luck with the getting the rpi3 to work with that display?

OldManNoob
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Joined: Sat Dec 24, 2016 2:35 pm

Re: 64x32 LED display

Sun Jul 23, 2017 9:15 am

Sadly, not yet as I've had a recent injury which got me knocked horizontally.

However, I'm still interested, and hope to have some form of display up soon enough.

If, however, anyone else out there has had any real success with the combination of Board and Driver by Embedded Adventures I would love to benefit form your experience...

Code on!

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OutoftheBOTS
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Re: 64x32 LED display

Tue Aug 01, 2017 11:07 am

I not sure if you guys have seen the addressable RGB leds. Each LED has a chip on it. The RPi just sends out a stream on data to the RGB pixels and the first pixel takes the first RGB data then passes on the the rest then the next RGB pixel takes the next bit of data and passes on the rest and so on till the end. You can chain together as many pixels as you want. see https://www.youtube.com/watch?v=JZDQ7BNRFM8

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rurwin
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Re: 64x32 LED display

Tue Aug 01, 2017 11:15 am

There's easier ways to get them too. I've got some in the post that are 8mm wired LEDs with four normal leads and you can get strings of various lengths either flat strips or like Christmas tree lights. I've re-engineered my light table several times. One of these days I'll actually finish it.

But 32x64 = 2048 LEDs would be a lot to drive serially. You might have update rate issues. You'll certainly not be able to run the power lines like that video. I make it a maximum of 60 amps.

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OutoftheBOTS
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Re: 64x32 LED display

Wed Aug 02, 2017 11:22 am

yes the number of LEDs would create some interesting challenges.

You could run them as rows of 64 LEDs with separate power to each row this would easily solve the amps problem. Although amps shouldn't be any higher for same brightness as the original LED matrix that was trying to be used.

You would have to also do something similar with the coms. I use the APA102 chipset LEDs they need 32bits/LED for brightness, blue, green and red values and have max serial baud rate of 400hz with clock line. I suppose you would need a little chip at the end of each row that you can com with super fast that can buffer the data the stream it up the row at the slower speed. Or another interesting hack could be to use the 24bit DPI parallel interface to send data to 24 seperate areas at once :)

suppose it isn't just a straight plug and play

I run little 320 x 240 res x 16bit colour LCD screens (76,800 pixels at 16 bits/pixel) by SPI serial coms but at a way faster baud rate 64Mhz and it get about 10 FPS

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